8 FISHERIES IMPACT

8.0.0.1 This chapter examines the direct and indirect impacts of DBL on the pond fishery and indirect impacts on intertidal fishery of Deep Bay. Direct impacts on the intertidal and subtidal fisheries are not within the scope of the current study - they are considered in the Fisheries Impact Assessment component of the associated Shenzhen Western Crossing.

8.1 Legislation, Policies, Plans, Standards and Criteria

8.1.0.1 Hong Kong government ordinances and regulations relevant to the consideration of fisheries under this study include the following:

• Fisheries Protection Ordinance (Cap. 171) and associated subsidiary legislation;
• Marine Fish Culture Ordinance (Cap. 353) and associated subsidiary legislation; and
• Environmental Impact Assessment Ordinance (Cap. 499) and associated Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM).

8.1.0.2 This assessment also takes note of the Categorization of Agricultural Land (Revised 1995) produced by the Agriculture, Fisheries and Conservation Department (AFCD), and of the international agreements listed in Chapter 7 where these are relevant to the conservation and exploitation of fisheries species and fishing grounds.

8.1.0.3 The information and assessment presented in this chapter are in accordance with the guidelines set forth in the TMEIAP, particularly Annexes 9 and 17. The TMEIAP guidelines are considered to be the most comprehensive available in Hong Kong for fisheries assessment.

8.2 Description of Environment

8.2.0 Literature Review

8.2.0.1 A field survey and literature review was conducted to determine existing conditions at the site and to identify sensitive fisheries receivers that may be affected by the project. The literature review included relevant available EIAs of projects in the northwest New Territories. The following studies were reviewed:

• Site Assessment Report (Ha Pak Nai) for Feasibility Study of Waste-to-Energy Incineration Facilities (CDM 1999).
• EIA for West Rail (Kowloon-Canton Railway Corporation): Final Initial Assessment Report - West Kowloon to Tuen Mun. (ERM, 1997).
• EIA of the West New Territories (WENT) Landfill (MHA 1987);
• Studies for dredging of WENT Fairway for Island East Transfer Station (ERL 1993);
• Shenzhen Western Corridor Investigation & Design - Final Working Paper on Fisheries Impact Assessment (OAP 2002);

8.2.0.2 The Site Assessment Report (Ha Pak Nai) for Feasibility Study of Waste-to-Energy Incineration Facilities (CDM 1999) reviewed fisheries in the Deep Bay area and fishponds in the northwest New Territories. The report also reviewed the 1989-1991 Port Survey Report and 1996-1997 Port Survey Report from AFCD. The latter provided the most up-to-date information available on inshore capture fisheries in Hong Kong. The report concluded that capture fishery, oyster culture and pond fishery had experienced a declining trend in the last few decades.

8.2.0.3 The EIA for West Rail (Kowloon-Canton Railway Corporation) assessed environmental impact from West Kowloon to Tuen Mun sections (ERM, 1997). The section from Yuen Long to Tuen Mun is relevant to this study. As the rail route mainly passes through residential areas, transportation infrastructure and flood control facilities, no information on fishery impact was given in the report.

8.2.0.4 The EIA for the WENT Landfill (MHA 1987) assessed capture fisheries in Deep Bay, including species caught and estimated value. Information was derived primarily from the AFCD Port Survey. Information on capture fishery is not relevant for this report.

8.2.0.5 Studies for the dredging of the WENT Fairway (ERL 1993) included a literature review on oyster beds and fisheries in the study area, which includes the current study area.

8.2.0.6 Shenzhen Western Corridor Investigation & Design - Final Working Paper on Fisheries Impact Assessment (OAP 2002) describes the coastal fishpond, oyster, intertidal and sub-tidal fisheries along and in the vicinity of the SWC alignment. The report concludes that the fisheries are of minor importance and are declining. Temporary and permanent impacts to fisheries associated with habitat loss are considered to be minor and no mitigation is recommended. Mitigation measures designed to prevent the possible degradation of water quality caused by sediment run-off during construction are considered adequate for the protection of fisheries.

8.2.1 Recognised Sites of Fisheries Importance

8.2.1.1 The following recognised sites of importance to capture or culture fisheries are located in the vicinity of the proposed DBL study area:

• Fish ponds on and near the site at Ngau Hom Shek;
• Fish ponds on and near the site west of Tseung Kong Wai and Ha Tsuen;
• Oyster culture beds at Ngau Hom Shek;
• Inter-tidal fishing activities at Ngau Hom Shek; and
• Gei wai (tidal shrimp ponds) and fish ponds in Inner Deep Bay are important aquaculture resources. These areas are located some 5-10 km from the site.

8.2.1.2 Due to their distance from the proposed DBL project area, no impacts to gei wai and Inner Deep Bay fish ponds, are expected as a result of the current project. The other recognised sites of importance to capture or culture fisheries are discussed in the following sections.

8.2.2 Baseline Fisheries Situation

Fish Pond Culture

8.2.2.1 Fish ponds in the North West New Territories are centred in Inner Deep Bay and north Yuen Long. A narrow, intermittent band of ponds extends from Inner Deep Bay along the south coast of Deep Bay. There are three areas with fish ponds which are likely to be impacted by the proposed DBL project, i.e. fishponds at Ngau Hom Shek, west Tseung Kong Wai and west Ha Tsuen. Field surveys were conducted to collect data on current fishpond culture activities in those areas. The pond owners or operators were interviewed for information on pond management, species cultured and yield. The surveyed pond areas were estimated based on field survey and topographic maps. Baseline information on fishponds in three areas is described below.

8.2.2.2 There were about 19 fishponds in the area of west Ha Tsuen (see Figures 7.4 & 7.5). All surveyed fishponds were abandoned or had been inactive for a few years with the exception of one pond (Pond No. 7) which was actively managed (Table 8.1). Two fish species, Tilapia Orechromis mossambicus and Catfish Clarias fuscus, were cultured in Pond No. 7 and the annual yield was approximately 5,000 kg. One full time employee managed the pond. Approximately 95% of the ponds were inactive or abandoned although shallow water was still naturally maintained in some of those ponds (Photo 8.1). A few inactive ponds were fully covered by grasses or floating water fern and a few ponds were abandoned for many years where wetland plants have colonised in the ponds (Photo 8.2).

8.2.2.3 Three fishponds with a total area of 1.68 ha at west Tseung Kong Wai were found to be active at the beginning of this study. The remainder of the adjacent ponds had been filled (see Figure 7.5). Orechromis mossambicus was the major species cultured in the active ponds (Pond No. 20, Photo 8.3) and annual yield was approximately 500 kg. No full time staff was employed to manage the pond. The filled ponds in the area were currently used as open storage or vehicle parks. Recent site visits revealed that Pond No. 20 was since filled, resulting in the latest status of two active fishponds with a total area of 1.55 ha as shown in Table 8.1.

8.2.2.4 Two fishponds at Ngau Hom Shek remained active and the rest of ponds nearby were abandoned (Figure 7.4, Pond Nos. 21 & 22, Photos 8.4 & 8.5). Fish species raised in the ponds were mainly Snakehead Ophiocephalus maculatus and Clarias fuscus. Annual yield ranged from approximately 400 to 800 kg. The two ponds were vulnerable to inundation in storm conditions due to their close proximity to Deep Bay.

Table 8.1 Summary of Fishpond Field Survey and Likely Habitat Loss (March 2000)

8.2.3 Oyster Culture and Inter-tidal Capture Fishery

8.2.3.1 Oyster beds on both shores of Deep Bay cultivated the Pacific oyster Crassostrea gigas for sale. Oyster rafts offshore were used for fattening following establishment at oyster beds. The oyster rafts off Ngau Hom Shek were not within the study area of the current project and were not examined in this assessment.

8.2.3.2 An oyster bed located on the mudflat some 80 m out from the mangrove edge at Ngau Hom Shek was found to be actively maintained by local villagers. It comprised of rows of cement pillar clutches (Photo 8.6). The pillar clutch rows were laid about one metre apart. All pillar clutches need to be pulled up from the mud and re-plugged about four to six times a year to avoid sediment smothering. This is especially critical after major storms. According to the owner of the oyster bed, it takes six years for the oysters to grow to a size suitable for commercial sale.

8.2.3.3 Oyster production has declined considerably in Deep Bay due to pollution and other reasons. Pollution affects oyster spat settlement and growth rates. Of 1,800 ha of oyster beds on the Hong Kong side of the Bay, only 600 ha were reported in active cultivation in 1992 (CDM 1999). Table 8.2 shows the changes in production and value of Hong Kong oyster culture operations in Deep Bay recent years. The quantity and value of production have shown a general decline in recent years.

Sources: CDM 1999

8.2.3.4 Apart for oyster culture, villagers at Ngau Hom Shek also fished the inter-tidal mudflat by net trapping. Vertical nets were set on wooden poles on the mudflat and about ten net traps connected to the vertical nets. During ebb tide, fishes, shrimps and crabs were caught in the traps. Daily capture varied from a few kg to 30 kg according to villagers. Mullet Mugil spp (fish), Parapenaeopsis spp (shrimp) and Scylla serrata (crab; Photo 8.7) were the main capture species. One-day capture was examined on 16 April 2000 and species, number and weight were given in the following Table 8.3.

8.2.4 Summary of Baseline Fisheries Situation

8.2.4.1 Fishpond culture was practiced along the DBL alignment. Fishponds within and around the study area were generally inactive or abandoned except for a few ponds which were managed for fish production. Within the study area, 32 ponds were identified. Among these, 5 with a total area of 2.14 ha were active and 20 with a total area of 5.2 ha were inactive or abandoned. The remaining 7 ponds were filled. An active oyster bed was located within the study area in the inter-tidal zone offshore Ngau Hom Shek.

8.2.4.2 In terms of capture fisheries, small-scale net trapping was carried out within the inter-tidal zone off Ngau Hom Shek. It is a family based traditional fishing activity and it is rarely seen elsewhere in Hong Kong.

8.3 Identification, Prediction and Evaluation of Potential Impacts

8.3.0.1 The significance of fisheries impacts is evaluated based primarily on the criteria set forth in Annex 9 of the EIAO-TM, as follows:

• Nature of impact;
• Size of area affected;
• Loss of fisheries resources/production;
• Destruction/disturbance of nursery and spawning grounds;
• Impact on fishing activity; and
• Impact on aquaculture activity.

8.3.1 Construction Stage

8.3.1.1 Potential sources of fisheries impacts during this stage of the project may be direct or indirect, and include:

• Fishpond loss caused by the site formation works;
• Oyster bed loss caused by the site formation works; and
• Water quality impacts caused by the site formation and construction works
  

Fish Pond Loss

8.3.1.2 Construction of the DBL would require the clearance and filling of fish ponds within the works area. Losses of ponds and pond area are shown in Table 8.1.

8.3.1.3 Part of pond No. 15 (affected area of 0.49 ha.) at West Ha Tsuen, which was inactive, would fall within the DBL route and would be permanently lost. Since there was no fish production from this permanently affected area, there should be no impact on pond fisheries.

8.3.1.4 Part of pond No. 24 (affected area 0.24 ha) at Ngau Hom Shek which had been abandoned, would fall within the DBL route and be resumed for works area and was counted as lost. However this loss was deemed temporary since the affected area would be restored. The unaffected area of this pond would be retained under a viaduct. Since this pond was identified as inactive/abandon with no fisheries production, there should be no impact on pond fisheries of this temporary occupied area.

• 8.3.1.5 By using the EIAO-TM Annex 9 criteria, the significance of impact on fisheries would be:
  Size of area affected - 0.73 ha of fishponds; representing approximately 10% of the total of both active and inactive/abandoned ponds. The ponds affected were all inactive or abandoned with no fish production.
• Loss of fisheries resources/production - 70% of fishponds in the study area are either inactive or abandoned. No active fishponds would be lost. Therefore there should be no impact on pond fisheries
• Destruction/disturbance of nursery and spawning grounds - not applicable;
• Impact on aquaculture activity - nil
  

Water Quality Impacts

8.3.1.6 Site formation works at Ngau Hom Shek may generate sediment which could affect oyster beds and capture fisheries in the inter-tidal zone. Construction site runoff and sewage effluent may also occur in the project area. Sediment and other pollution could potentially kill oyster beds through suffocation and other effects. However, such indirect impacts could be reduced through the implementation of appropriate mitigation measures. To minimise the risk of damage to offsite ponds or fishing grounds from site activities, a boundary fence or hoarding should be erected to divide the site from nearby ponds. Site runoff should be directed away from nearby inter-tidal fishing grounds and oyster bed through settlement ponds (silt traps). With such mitigation, any indirect impact on inter-tidal net trapping and oyster bed would be minimal. There would be no direct loss of oyster bed or inter-tidal net trapping area from the DBL project.

8.3.1.7 Predicted impacts on fishpond production due to water quality changes is likely to be minimal, since the small number of ponds likely to be affected were either inactive or abandoned ponds. To minimise the risk of damage to offsite ponds from site activities, a boundary fence or hoarding should be erected to divide the site from nearby ponds. Site runoff should be directed away from nearby fish ponds. Given these mitigation measures, potential damage to off-site fishpond habitats the site was predicted to be minor.

Summary of Construction Impacts

8.3.1.8 The potential impacts of DBL construction upon fisheries are summarised in Table 8.4.

8.3.2 Operational Stage

8.3.2.1 Stormwater runoff from the highway at Ngau Hom Shek, if discharged directly into Deep Bay, could affect nearby fishing grounds and oyster beds by introducing sediments and contaminants such as metals and oils leaked from vehicles. This impact would be reduced by implementing a range of water quality control measures (see Chapter 4).

8.3.2.2 Accidental spillage of fuel and/or chemicals due to traffic accidents could affect nearby fishing grounds or oyster culture sites in Deep Bay. Spill response plans should be developed to handle such incidents.

8.3.2.3 Potential impacts upon pond fisheries during the operational stage were not considered significant. A range of water quality control measures would be implemented to ensure that there is no contamination of ponds or watercourses from road runoff (see Chapter 4). The affected ponds were in any case small in size and were abandoned.

Summary of Operational Impacts

8.3.2.4 The potential impacts of DBL operation upon fisheries are summarised in Table 8.5.